Update Documentation

[amccool]

update the documentation to reflect the removal of the _type field and the change of the index name to make compatible with ES 6.x

[dzmitry-lahoda]

I see that nuget still uses ES client 2.x. Better start to use 5+. Better same as https://github.com/amccool/ElasticSearch.Extensions.Logging.

I see Orleans 1.5.1 is used. So updated needed either.

[amccool]

#15 brings us to Orleans 2.3. The Upgrade to the ES client is still outstanding